The invention relates to a fuel tank for a motor vehicle, having a wall manufactured from plastic, in particular by injection molding.
Fuel tanks of this type are frequently used in today""s motor vehicles and are therefore known. In this case, the fuel tank is generally composed of a plurality of shell parts which are manufactured by injection molding and are then welded to one another. This enables complicated fuel tank shapes to be produced very simply and built-in parts to be inserted in them. Furthermore, because its wall is made of plastic the fuel tank is of very low weight.
A disadvantage of the known fuel tank is that it is very permeable for fuel vapors. Fuel can therefore pass through the wall into the environment.
The invention is based on the problem of designing a fuel tank of the type mentioned at the beginning in such a manner that it is of a particularly low weight and that as little fuel vapor as possible can penetrate the wall.
According to the invention, this problem is solved by at least one permeation barrier for fuel vapors being arranged on the wall.
This design means that fuel vapors cannot penetrate the wall, or can only do so in small amounts, in accordance with the design of the permeation barrier. In this case, the permeation barrier consists of a material having particularly low permeation for the fuel. Since the wall in the known fuel tank is manufactured from plastic, the fuel tank according to the invention is of a low weight and can be manufactured in virtually any desired shape.
The permeation barrier could be formed on the outside of the wall as a coat of paint, for example. Since the outside of the fuel tank mounted in the motor vehicle is subject to mechanical stresses, the permeation barrier may be damaged and fuel may permanently penetrate the wall. The permeation barrier particularly reliably and permanently prevents fuel from penetrating the wall if the permeation barrier is arranged on the inside of the wall manufactured from plastic. In addition, the application of the permeation barrier in current fuel tanks can take place before they are welded together, since the permeation barrier does not require any changes to or adaptations of fixing devices and connecting pieces arranged on the outside of the fuel tank.
The permeation barrier can be applied to the wall in a very simple manner during large-scale manufacturing of the fuel tank according to the invention if said barrier has a film manufactured from a particularly permeation-tight material.
According to another advantageous development of the invention, the permeation barrier contributes to the stability of the wall if the permeation barrier has shell parts having particularly low permeability for fuel vapors.
According to another advantageous development of the invention, the wall is virtually impenetrable for fuel if the permeation barrier is manufactured from metal. Sheet steel or sheet aluminum, for example, are suitable in this case.
According to another advantageous development of the invention, a contribution is made to further reducing the weight of the wall if the permeation barrier is manufactured from a particularly permeation-tight plastic. In this case, the permeation barrier may, of course, be of multilayered construction. The permeation barrier manufactured from plastic or from metal may, for example, be inserted into the injection mold of the shell parts for the wall and subsequently encapsulated by injection molding.
Lines and components to be fitted in today""s fuel tanks can be arranged in the fuel tank in a simple manner if lines and components to be installed in the fuel tank are fixed to the permeation barrier.
A seal, for example, could be arranged between two abutting regions of shell parts of the permeation barrier. However, according to another advantageous development of the invention, a seal of this type can be avoided if the shell parts are welded to one another at their abutting regions.